Thomas Moore is looking forward to finally coming face-to-face with James Ford Seale, a Ku Klux Klansman who came back from the dead. "I want to look at him," he said. "I want to tell him about the pain he caused me and my family."

Mr Moore, 63, a retired sergeant-major, recalled the day he found out that Mr Seale was still alive. "I was so happy. We thought he was dead - and so did everyone else."

The trial opens here today of Mr Seale, 71, a former worker in a paper plant, crop-duster and policeman, accused of kidnapping and conspiracy in relation to the murder of two black teenagers in 1964, one of them Mr Moore's brother. According to the indictment, the two 19-year-olds, Charles Moore and Henry Dee, were kidnapped by the White Knights of the Ku Klux Klan, tortured and dumped in the Mississippi, Moore tied to a jeep engine block, and, according to an FBI informant at the time, still breathing.

The killings marked the beginning of a summer of madness, as the KKK responded to the civil rights movement with the fiery crosses, church bombings and murders depicted in Alan Parker's 1989 film Mississippi Burning.

The Seale prosecution could be among the last of the KKK trials. Although the justice department has promised to re-open cases, witnesses are dying off and files have been lost.

Now living in Colorado, Mr Moore had been brought up in Franklin County, one of the strongholds of the White Knights. He returned in 2005 with a Canadian film-maker, David Ridgen, to investigate the murders. Pulling up at a petrol station for an egg and sausage sandwich, he met by chance a distant cousin, Kenny Byrd.

Mr Moore explained why they were there and said it was a pity that Mr Seale, who had been one of the main suspects, was dead. His family had been saying so since 2000. The local Clarion-Ledger had reported it as fact: so too had the Los Angeles Times. Mr Byrd replied: "Hell no, he lives over there."

Mr Moore traced lost files, spoke to potential witnesses, harassed former Klansmen, mobilised the African-American community and successfully campaigned to have the FBI re-open the case.

Mr Seale is expected to plead not guilty in a trial expected to last about a fortnight. If found guilty, he faces life sentences.

Mississippi is different these days, at least on the surface. It is evident to anyone arriving at the airport at Jackson, now called Jackson-Evers International in recognition of the civil rights leader, Medgar Evers, who was assassinated in 1963. It is evident, too, in the fact that the judge who will try the case is African-American, Henry Wingate.

But Heidi Beirich, deputy director of intelligence at a Jackson-based civil rights group, the Southern Poverty Law Centre, which investigates hate crimes, cautioned that although the KKK and institutionalised racism is mainly a thing of the past, Mississippi still has problems. She noted that when the state voted in 2002 to retain the Confederate flag, a symbol of hate for African-Americans, the divide was on racial grounds. African-Americans in the state continue to live in the poorest areas, with the worst schools.

"As far as the Klan is concerned, its heyday is definitely in the past. It hit its peak in the 1920s at 4 million. The number of Klansmen is way down: we estimate 5,000-6,000. It is not a cohesive organisation any longer: it is fragmented. They are no longer capable of the kind of terror they rained down on the South in the 1950s and 1960s," Ms Beirich said.

But the sense of dread inspired by the KKK has not gone completely. Ridgen, who put together a documentary Mississippi Cold Case, said: "The psychological threat was always there. There was fear every time in Franklin County. We never took the same route. We never told anyone in advance about coming."

At the trial, the key witness is likely to be a former Klansman, Charles Edwards, a suspect at the time, who is expected to give evidence against Mr Seale in return for immunity. Former FBI agents who carried out a fairly thorough investigation at the time are also scheduled to testify. After their investigation in 1964, they handed the case over to the local justice department who, as was not unusual at the time, quickly dropped it.

No real explanation has been given for the killings. Klansmen at the time told the FBI that Mr Dee had been peeping at one of their wives while others alleged gun smuggling into a black church. The indictment suggests otherwise: "The White Knights ... targeted for violence African-Americans they believed were involved in civil rights activity in order to intimidate and retaliate against such individuals."

Mr Dee's sister, Thelma Collins, who now lives in Louisiana, said yesterday she could not remember him being involved in any civil rights activity. "He was quiet, never said much," she recalled. She is saddened that the case has taken 43 years to come to court: "It is pitiful that those boys were killed and no one did anything about it."

Like Mrs Collins, Mr Moore will be given his chance to make a victim's statement in court. He said: "I want to tell how it is to go without a brother, my son without an uncle, how Charles never had the opportunity to make mistakes, to live his life."

Backstory

The reopening of racist murder cases from the 1960s in the South began in 1990 when a white supremacist, Byron La Beckwith, was indicted and eventually jailed for the assassination in 1963 of Medgar Evers, then chairman in Mississippi of the National Association for the Advancement of Colored People. This encouraged the FBI and local justice departments to look again at unsolved cases. Since then, there have been six prosecutions in Mississippi, including Mr Seale's today. Authorities in seven states have re-examined a total of 29 killings and made 29 arrests, leading to 22 convictions.

One of the most prominent was the trial and jailing in 2001 of Thomas Blanton and Bobby Frank Cherry for the 1963 bombing of the 16th Street Baptist Church in Birmingham, Alabama, which killed four young girls. The revulsion created by the bombing helped turn public opinion behind the civil rights movement. In 2005, Edgar Ray Killen, 80, was jailed for the murder of the three civil rights activists depicted in Mississippi Burning. But the reality is that there may not be many more cases brought to court: elderly witnesses are dying off and records of crimes have been lost.